We have examined the role of the environment on the interactions between transmembrane helices using, as a model system, the dimerization of the glycophorin A transmembrane helix. In this study we have focused on micellar environments and have examined a series of detergents that include a range of alkyl chain lengths, combined with ionic, zwitterionic, and nonionic headgroups. For each we have measured how the apparent equilibrium constant depends on the detergent concentration. In two detergents we also measured the thermal sensitivity of the equilibrium constant, from which we derive the van't Hoff enthalpy and entropy. We show that several simple models are inadequate for explaining our results; however, models that include the effect of detergent concentration on detergent binding are able to account for our measurements. Our analysis suggests that the effects of detergents on helix association are due to a pair of opposing effects: an enthalpic effect, which drives association as the detergent concentration is increased and which is sensitive to the chemical nature of the detergent headgroup, opposed by an entropic effect, which drives peptide dissociation as the detergent concentration is raised. Our results also indicate that the monomer-monomer interface is relatively hydrophilic and that association within detergent micelles is driven by the enthalpy change. The wide variations in glycophorin a dimmer, stability with the detergent used, together with the realization that this results from the balance between two opposing effects, suggests that detergents might be selected that drive association rather than dissociation of peptide dimers.
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http://dx.doi.org/10.1016/S0006-3495(03)74728-6 | DOI Listing |
Transl Anim Sci
December 2024
Institute of Animal Science, Beef Cattle Research Center, Sertãozinho, Brazil.
The objective of this study was to evaluate the efficacy of using 3 yeast-based additives as an alternative to sodium monensin on rumen fermentation parameters using a dual-flow continuous fermentation system. Ten fermenters (1,223 ± 21 mL) were used in 2 simultaneous 5 × 5 Latin squares arrangement with 3 periods of 10 d each, with 7 d for diet adaptation and 3 d for sample collections. Each Latin square assigning either a low or high level of concentrate to beef cattle diets, with 5 specified treatments: Control: no additives; Blend 1: yeast culture (), beta-glucans, fructooligosaccharides, galactooligosaccharides, and mannanoligosaccharides [1,600 mg/kg dry matter (DM)]; Blend 2: Beta-glucan and mannanoligosaccharide fractions from (1,600 mg/kg DM); Yeast Cells: hydrolyzed, inactivated, and spray-dried yeast cells (; 2,133 mg/kg DM); monensin (25 mg/kg DM).
View Article and Find Full Text PDFInt J Biol Macromol
December 2024
Biochemistry and Biotechnology Laboratory, Central Leather Research Institute, Council of Scientific and Industrial Research (CSIR), Adyar, Chennai 600020, India; Academy of Scientific and Innovative Research (AcSIR), Ghaziabad 201002, India. Electronic address:
Keratin is an important biopolymer used to develop biomaterials for biomedical and industrial applications. Traditional keratin extraction methods involve the removal of surface lipids using organic solvents, detergents, and energy-intensive processes that often compromise the purity of the extracted keratin. In the present study, wool fibers were microbially disintegrated to isolate cortical cells, achieving a maximum yield of 61.
View Article and Find Full Text PDFAnimals (Basel)
November 2024
College of Animal Sciences and Technology, Northeast Agricultural University, Harbin 150030, China.
The objective of this study was to assess the impact of , , and a lignocellulolytic enzyme system on the nutritional value, fermentation profiles, rumen digestion, and bacterial community of fresh waxy corn stalk silage. Fresh waxy corn stalks harvested after 90 days of growth were treated with no additives (CON), compound multiple lactobacilli (ML, comprising at 1.0 × 10 cfu/g fresh weight and at 1.
View Article and Find Full Text PDFAnimals (Basel)
November 2024
College of Animal Science and Technology, Jilin Agricultural University, Changchun 130118, China.
This study aimed to explore the effects of dietary fiber level and breed on the growth performance, nutrient utilization, intestinal morphology, slaughter performance, and meat quality of finishing pigs using fermented corn straw (FCS) as the fiber source. The experiment employed a 2 × 4 factorial design, selecting 96 Songliao Black (SLB) and Duroc × Landrace × Yorkshire (DLY) crossbred finishing pigs (a total of 192 pigs, with an initial body weight of 60.52 ± 4.
View Article and Find Full Text PDFPLoS One
December 2024
Bioprocess Engineering Group, Institute of Industrial and Environmental Biotechnology, National Institute of Genetic Engineering and Biotechnology (NIGEB), Tehran, Iran.
Proteases as one of the most significant categories of commercial enzymes, serve nowadays as the key ingredients in detergent formulations. Therefore, identifying detergent-compatible proteases with better properties is a continuous exercise. Accordingly, we were interested in the recombinant production and characterization of protease 3075 as a novel enzyme from thermophilic indigenous Cohnella sp.
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